Assigning processing elements to stream computing servers

ABSTRACT

The present invention provides a computer implemented method, system, and computer program product of assigning processing elements to stream computing servers with respect to external computing resources. In an embodiment, the present invention includes receiving performance requirements data of a plurality of processing elements of a computer software application, where the processing elements are configured to execute on a stream computing system, receiving resource characteristics data of at least one computing resource external to the stream computing system, receiving performance characteristics data of stream computing servers, and in response to receiving a request from at least one processing element to communicate with the at least one computing resource external to the stream computing system, assigning the at least one processing element to at least one stream computing server as a function of the performance requirements data, the resource characteristics data, and the performance characteristics data.

BACKGROUND

The present disclosure relates to computer systems, and morespecifically, to assigning processing elements to stream computingservers with respect to external computing resources.

SUMMARY

The present invention provides a computer implemented method, a system,and a computer program product of assigning processing elements tostream computing servers with respect to external computing resources.In an exemplary embodiment, the computer implemented method, the system,and the computer program product include (1) receiving, by a computersystem, performance requirements data of a plurality of processingelements of a computer software application, where the processingelements are configured to execute on a stream computing system, wherethe stream computing system includes a network of stream computingservers, (2) receiving, by the computer system, resource characteristicsdata of at least one computing resource external to the stream computingsystem, (3) receiving, by the computer system, performancecharacteristics data of the stream computing servers, and (4) inresponse to receiving by the computer system a request from at least oneprocessing element among the processing elements to communicate with theat least one computing resource external to the stream computing system,assigning, by the computer system, the at least one processing elementto at least one stream computing server among the stream computingservers as a function of the performance requirements data, the resourcecharacteristics data, and the performance characteristics data.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A depicts a flowchart in accordance with an exemplary embodimentof the present invention.

FIG. 1B depicts a block diagram in accordance with an exemplaryembodiment of the present invention.

FIG. 2 depicts a flowchart in accordance with an exemplary embodiment ofthe present invention.

FIG. 3 depicts a block diagram in accordance with an embodiment of thepresent invention.

FIG. 4 depicts a block diagram in accordance with an embodiment of thepresent invention.

FIG. 5 depicts a block diagram in accordance with an embodiment of thepresent invention.

FIG. 6 depicts a block diagram in accordance with an embodiment of thepresent invention.

FIG. 7 depicts a block diagram in accordance with an embodiment of thepresent invention.

FIG. 8 depicts a block diagram in accordance with an embodiment of thepresent invention.

FIG. 9 depicts a computer system in accordance with an exemplaryembodiment of the present invention.

FIG. 10 depicts a cloud computing environment according to variousembodiments of the present invention.

FIG. 11 depicts abstraction model layers according to variousembodiments of the present invention.

DETAILED DESCRIPTION

The present invention provides a computer implemented method, a system,and a computer program product of assigning processing elements tostream computing servers with respect to external computing resources.In an exemplary embodiment, the computer implemented method, the system,and the computer program product include (1) receiving, by a computersystem, performance requirements data of a plurality of processingelements of a computer software application, where the processingelements are configured to execute on a stream computing system, wherethe stream computing system includes a network of stream computingservers, (2) receiving, by the computer system, resource characteristicsdata of at least one computing resource external to the stream computingsystem, (3) receiving, by the computer system, performancecharacteristics data of the stream computing servers, and (4) inresponse to receiving by the computer system a request from at least oneprocessing element among the processing elements to communicate with theat least one computing resource external to the stream computing system,assigning, by the computer system, the at least one processing elementto at least one stream computing server among the stream computingservers as a function of the performance requirements data, the resourcecharacteristics data, and the performance characteristics data. In anembodiment, the computer system includes a stream computing managersystem (e.g., a stream runtime system). In a particular embodiment, thecomputer system is a stream computing manager system (e.g., a streamruntime system). In an embodiment, the computer software applicationincludes a stream computing application. In a particular embodiment, thecomputer software application is a stream computing application. In anembodiment, the network of stream computing servers includes the streamcomputing servers logically interconnected in a computer networkconfiguration. In a particular embodiment, the network of streamcomputing servers is a cluster of the stream computing servers. In anembodiment, the at least one computing resource external to the streamcomputing system includes a computer data source/sink. In a particularembodiment, the at least one computing resource external to the streamcomputing system is a computer data source/sink. In a particularembodiment, the computer data source/sink is at least one of a computerdatabase, a computer message queue, a computer storage device, a sensor,a camera, and a microphone. For example, the computer data source/sinkcould be any one of a computer database, a computer message queue, acomputer storage device, a sensor, a camera, and a microphone.

Definitions

Stream Computing

Stream-based computing, stream-based database computing, and streamcomputing systems are developing technologies for database systems.Current stream-based computing systems, stream-based database computingsystems, and stream computing systems allow users to create computersoftware applications that process and query streaming tuples of databefore such data reaches a database file. Stream-based computingsystems, stream-based database computing systems, and stream computingsystems allow users to specify processing logic to apply to inbound datarecords while they are “in flight”, with the results being available ina very short amount of time, often in fractions of a second.

A stream computing system analyzes multiple data streams from manysources live, where “stream” means the stream computing system pulls instreams of data, processes the data, and streams it back out as a singleflow.

In a stream computing application, stream operators are connected to oneanother such that data flows from one stream operator to the next (e.g.,over a TCP/IP socket). When a stream operator receives data, the streamoperator may perform operations, such as analysis logic, which maychange the tuple by adding or subtracting attributes, or updating thevalues of existing attributes within the tuple. When the analysis logicis complete, the stream operator sends a new tuple to the next streamoperator.

Processing Elements

A stream computing system achieves scalability by distributing acomputer software application/stream computing application across nodesby creating executables (i.e., processing elements), as well asreplicating processing elements on multiple nodes and load balancingamong them. Stream operators in a stream computing application can befused together to form a processing element that is executable, suchthat the processing elements can share a common process space, that mayresult in faster communication between stream operators than isavailable using inter-process communication techniques (e.g., using aTCP/IP socket). Further, processing elements can be inserted or removeddynamically from an operator graph representing the flow of data throughthe stream computing application. Also, a particular stream operator maynot reside within the same operating system process as other streamoperators. In addition, stream operators in the same operator graph maybe hosted on different nodes (e.g., on different compute nodes) or ondifferent cores of a compute node. In stream computing, a streamcomputing application is broken into smaller units of work that aredistributed out to a cluster of machines, where the smaller units ofwork may be called processing elements.

Tuples

Data flows from one stream operator to another in the form of a “tuple”,where a tuple is a sequence of one or more attributes associated with anentity. Attributes may be any of a variety of different types (e.g.,integer, float, Boolean, string), where the attributes may be ordered. Atuple may also include metadata (i.e., data about the tuple). Also, atuple may be extended by adding one or more additional attributes ormetadata to it. The terms “stream” or “data stream” refers to a sequenceof tuples. Generally, a stream may be considered a pseudo-infinitesequence of tuples.

In a stream computing application, tuples are received and output bystream operators and processing elements. An input tuple correspondingwith a particular entity that is received by a stream operator orprocessing element, however, is generally not considered to be the sametuple that is output by the stream operator or processing element, evenif the output tuple corresponds with the same entity or data as theinput tuple. An output tuple need not be changed in some way from theinput tuple.

Nonetheless, an output tuple may be changed in some way by a streamoperator or processing element, where an attribute or metadata may beadded, deleted, or modified. For example, a tuple will often have two ormore attributes. A stream operator or processing element may receive thetuple having multiple attributes and output a tuple corresponding withthe input tuple. The stream operator or processing element may onlychange one of the attributes so that all of the attributes of the outputtuple except one are the same as the attributes of the input tuple.Generally, a particular tuple output by a stream operator or processingelement may not be considered to be the same tuple as a correspondinginput tuple even if the input tuple is not changed by the processingelement. However, an output tuple that has the same data attributes oris associated with the same entity as a corresponding input tuple may beconsidered as the same tuple.

Processing Tuples

Stream computing applications may handle large volumes of data that needto be processed efficiently and in real time. For example, a streamcomputing application may continuously ingest and analyze hundreds ofthousands of messages per second and up to petabytes of data per day.Accordingly, each stream operator in a stream computing application maybe required to process a received tuple within fractions of a second.Unless the stream operators are located in the same processing element,it may be necessary to use an inter-process communication path each timea tuple is sent from one stream operator to another, where suchinter-process communication paths can be a critical resource in a streamcomputing application. Efficient use of inter-process communicationbandwidth could speed up processing.

An operator graph could be an execution path for a plurality of streamoperators to process a stream of tuples. In addition to streamoperators, the operator graph could refer to an execution path forprocessing elements and the dependent stream operators of the processingelements to process the stream of tuples. Generally, the operator graphcould have a plurality of stream operators that produce a particular endresult (e.g., calculate an average). An operator graph may be a lineararrangement of processing elements and/or operators, or it may includeone or more distinct execution paths, also known as sub-processes,methods, or branches.

Jobs

A stream computing application could have several “jobs” (i.e., specificapplications) executing in parallel, where each job could be associatedwith an individual data flow. These individual data flows could bethought of as separate operator graphs or portions of the same logicaloperator graph. In either case, a job or administrator could specify aparticular stream of data (e.g., a connection between processingelements or operators in the operator graph) as “exportable”, such thata different job could then dynamically connect to the exportable datastream (i.e., import the data stream) (referred to as a “dynamicconnection” because both jobs are currently executing when they begin toshare the data stream).

Distributing Work

Often, processing elements are distributed across a cluster/network ofcomputer systems in a manner/configuration that best suits performanceas dictated by a developer of the stream computing application (e.g.,using constructs available via a config statement). Some configurationoptions are available to the developer are (a) to join a set ofoperators together to form a single processing element, (b) to hostcollocate (i.e., placing operators on the same node), or (c) to excollocate certain operators (i.e., placing operators on differentnodes). Such configuration options could be used in productionapplications.

Need to Assign Processing Elements with respect to External ComputingResources

It has been observed that such stream computing configuration optionscould be limiting in nature when stream computing applications involve(i) reading/writing from a database and/or a message queue, and/or (ii)writing to shared disk. There is a need to be able to deploy processingelements as they relate to external computing resources (e.g., datasources/sinks).

Referring to FIG. 1A, in an exemplary embodiment, the present inventionis configured to perform an operation 110 of receiving, by a computersystem, performance requirements data of a plurality of processingelements of a computer software application, where the processingelements are configured to execute on a stream computing system, wherethe stream computing system includes a network of stream computingservers, an operation 112 of receiving, by the computer system, resourcecharacteristics data of at least one computing resource external to thestream computing system, an operation 114 of receiving, by the computersystem, performance characteristics data of the stream computingservers, and an operation 116 of in response to receiving by thecomputer system a request from at least one processing element among theprocessing elements to communicate with the at least one computingresource external to the stream computing system, assigning, by thecomputer system, the at least one processing element to at least onestream computing server among the stream computing servers as a functionof the performance requirements data, the resource characteristics data,and the performance characteristics data.

In an embodiment, the present invention places operators/processingelements onto stream computing servers based on at least externalinterfaces with which such operators communicate. In an embodiment, thepresent invention places operators/processing elements onto streamcomputing servers at application start up time and in some ongoingdynamic manner at runtime. For example, the present invention could useboth historical access times to a given source/computing resource fromdifferent machines/stream computing servers as well as current runtimesusing run time checks such as “ping” (e.g., heartbeat checks to theexternal location). In an embodiment, the present invention conservesavailable bandwidth on one or more inter-process communication paths.

In an exemplary embodiment, the computer system is a standalone computersystem, such as computer system 900 shown in FIG. 9, a network ofdistributed computers, where at least some of the computers are computersystems such as computer system 900 shown in FIG. 9, or a cloudcomputing node server, such as computer system 900 shown in FIG. 9. Inan embodiment, the computer system is a computer system 900 as shown inFIG. 9, that executes an assigning processing elements to streamcomputing servers with respect to external computing resources script orcomputer software application that carries out the operations of atleast method 100. In an embodiment, the computer system is a computersystem/server 912 as shown in FIG. 9, that executes an assigningprocessing elements to stream computing servers with respect to externalcomputing resources script or computer software application that carriesout the operations of at least method 100. In an embodiment, thecomputer system is a processing unit 916 as shown in FIG. 9, thatexecutes an assigning processing elements to stream computing serverswith respect to external computing resources script or computer softwareapplication that carries out the operations of at least method 100. Inan embodiment, the computer system is a stream computing manager system(e.g., a stream runtime system) that executes an assigning processingelements to stream computing servers with respect to external computingresources script or computer software application that carries out theoperations of at least method 100. In an embodiment, the computer systemis a computer system 900 as shown in FIG. 9, that executes an assigningprocessing elements to stream computing servers with respect to externalcomputing resources script or computer software application that carriesout at least operations 110, 112, 114, and 116. In an embodiment, thecomputer system is a computer system/server 912 as shown in FIG. 9, thatexecutes an assigning processing elements to stream computing serverswith respect to external computing resources script or computer softwareapplication that carries out at least operations 110, 112, 114, and 116.In an embodiment, the computer system is a processing unit 916 as shownin FIG. 9, that executes an assigning processing elements to streamcomputing servers with respect to external computing resources script orcomputer software application that carries out at least operations 110,112, 114, and 116. In an embodiment, the computer system is a streamcomputing manager system/stream manager (e.g., a stream runtime system)that executes an assigning processing elements to stream computingservers with respect to external computing resources script or computersoftware application that carries out at least operations 110, 112, 114,and 116.

Referring to FIG. 1B, in an exemplary embodiment, the present inventionincludes a receiver 130 and an assigner 140. In an embodiment, receiver130 is configured to receive performance requirements data 150 of aplurality of processing elements 154 of a computer software application152 (e.g., a stream computing application), where processing elements154 are configured to execute on a stream computing system 156, wherestream computing system 156 includes a network of stream computingservers 158. In an embodiment, receiver 130 includes a computer system,such as computer system 900 as shown in FIG. 9, performing operation110. In an embodiment, receiver 130 includes a computer system, such ascomputer system/server 912 as shown in FIG. 9, performing operation 110.In an embodiment, receiver 130 includes a computer system, such asprocessing unit 916 as shown in FIG. 9, performing operation 110. In anembodiment, receiver 130 is a stream computing manager system (e.g., astream runtime system) performing operation 110. In an embodiment,receiver 130 is implemented as computer software executing on a computersystem, such as computer system 900 as shown in FIG. 9, such that thecomputer system performs operation 110. In an embodiment, receiver 130is implemented as computer software executing on a computer system, suchas computer system/server 912 as shown in FIG. 9, such that the computersystem performs operation 110. In an embodiment, receiver 130 isimplemented as computer software executing on a computer system, such asprocessing unit 916 as shown in FIG. 9 such that the computer systemperforms operation 110. In an embodiment, receiver 130 is implemented ascomputer software executing on a computer system, such as a streamcomputing manager system (e.g., a stream runtime system), such that thecomputer system performs operation 110. In an embodiment, receiver 130performs operation 110 as computer software executing on aprocessor/processing unit of receiver 130.

In an embodiment, receiver 130 is configured to receive resourcecharacteristics data 160 of at least one computing resource 162 externalto stream computing system 156. In an embodiment, receiver 130 includesa computer system, such as computer system 900 as shown in FIG. 9,performing operation 112. In an embodiment, receiver 130 includes acomputer system, such as computer system/server 912 as shown in FIG. 9,performing operation 112. In an embodiment, receiver 130 includes acomputer system, such as processing unit 916 as shown in FIG. 9,performing operation 112. In an embodiment, receiver 130 is a streamcomputing manager system (e.g., a stream runtime system) performingoperation 112. In an embodiment, receiver 130 is implemented as computersoftware executing on a computer system, such as computer system 900 asshown in FIG. 9, such that the computer system performs operation 112.In an embodiment, receiver 130 is implemented as computer softwareexecuting on a computer system, such as computer system/server 912 asshown in FIG. 9, such that the computer system performs operation 112.In an embodiment, receiver 130 is implemented as computer softwareexecuting on a computer system, such as processing unit 916 as shown inFIG. 9 such that the computer system performs operation 112. In anembodiment, receiver 130 is implemented as computer software executingon a computer system, such as a stream computing manager system (e.g., astream runtime system), such that the computer system performs operation112. In an embodiment, receiver 130 performs operation 112 as computersoftware executing on a processor/processing unit of receiver 130.

In an embodiment, receiver 130 is configured to receive performancecharacteristics data 170 of stream computing servers 158. In anembodiment, receiver 130 includes a computer system, such as computersystem 900 as shown in FIG. 9, performing operation 114. In anembodiment, receiver 130 includes a computer system, such as computersystem/server 912 as shown in FIG. 9, performing operation 114. In anembodiment, receiver 130 includes a computer system, such as processingunit 916 as shown in FIG. 9, performing operation 114. In an embodiment,receiver 130 is a stream computing manager system (e.g., a streamruntime system) performing operation 114. In an embodiment, receiver 130is implemented as computer software executing on a computer system, suchas computer system 900 as shown in FIG. 9, such that the computer systemperforms operation 114. In an embodiment, receiver 130 is implemented ascomputer software executing on a computer system, such as computersystem/server 912 as shown in FIG. 9, such that the computer systemperforms operation 114. In an embodiment, receiver 130 is implemented ascomputer software executing on a computer system, such as processingunit 916 as shown in FIG. 9 such that the computer system performsoperation 114. In an embodiment, receiver 130 is implemented as computersoftware executing on a computer system, such as a stream computingmanager system (e.g., a stream runtime system), such that the computersystem performs operation 114. In an embodiment, receiver 130 performsoperation 114 as computer software executing on a processor/processingunit of receiver 130.

In an embodiment, assigner 140 is configured to assign at least oneprocessing element 155 among processing elements 154 to at least onestream computing server 159 among stream computing servers 158 as afunction of performance requirements data 150, resource characteristicsdata 160, and performance characteristics data 170, in response toreceiver 130 receiving a request 180 from at least one processingelement 155 to communicate with at least one computing resource 162external to stream computing system 156. In an embodiment, assigner 140includes a computer system, such as computer system 900 as shown in FIG.9, performing operation 116. In an embodiment, assigner 140 includes acomputer system, such as computer system/server 912 as shown in FIG. 9,performing operation 116. In an embodiment, assigner 140 includes acomputer system, such as processing unit 916 as shown in FIG. 9,performing operation 116. In an embodiment, assigner 140 is a streamcomputing manager system (e.g., a stream runtime system) performingoperation 116. In an embodiment, assigner 140 is implemented as computersoftware executing on a computer system, such as computer system 900 asshown in FIG. 9, such that the computer system performs operation 116.In an embodiment, assigner 140 is implemented as computer softwareexecuting on a computer system, such as computer system/server 912 asshown in FIG. 9, such that the computer system performs operation 116.In an embodiment, assigner 140 is implemented as computer softwareexecuting on a computer system, such as processing unit 916 as shown inFIG. 9 such that the computer system performs operation 116. In anembodiment, assigner 140 is implemented as computer software executingon a computer system, such as a stream computing manager system (e.g., astream runtime system), such that the computer system performs operation116. In an embodiment, assigner 140 performs operation 116 as computersoftware executing on a processor/processing unit of assigner 140.

Receiving Performance Requirements Data

In an exemplary embodiment, the receiving the performance requirementsdata includes receiving the performance requirements data at one of astartup time of the computer software application and a runtime of thecomputer software application. In an exemplary embodiment, receivingoperation 110 includes an operation of receiving the performancerequirements data at one of a startup time of the computer softwareapplication and a runtime of the computer software application. In anembodiment, receiver 130 is configured to receive performancerequirements data 150 at one of a startup time of computer softwareapplication 152 and a runtime of computer software application 152. Inan embodiment, receiver 130 includes a computer system, such as computersystem 900 as shown in FIG. 9, receiving performance requirements data150 at one of a startup time of computer software application 152 and aruntime of computer software application 152. In an embodiment, receiver130 includes a computer system, such as computer system/server 912 asshown in FIG. 9, receiving performance requirements data 150 at one of astartup time of computer software application 152 and a runtime ofcomputer software application 152. In an embodiment, receiver 130includes a computer system, such as processing unit 916 as shown in FIG.9, receiving performance requirements data 150 at one of a startup timeof computer software application 152 and a runtime of computer softwareapplication 152. In an embodiment, receiver 130 is a stream computingmanager system (e.g., a stream runtime system) receiving performancerequirements data 150 at one of a startup time of computer softwareapplication 152 and a runtime of computer software application 152.

In an embodiment, receiver 130 is implemented as computer softwareexecuting on a computer system, such as computer system 900 as shown inFIG. 9, such that the computer system receives performance requirementsdata 150 at one of a startup time of computer software application 152and a runtime of computer software application 152. In an embodiment,receiver 130 is implemented as computer software executing on a computersystem, such as computer system/server 912 as shown in FIG. 9, such thatthe computer system receives performance requirements data 150 at one ofa startup time of computer software application 152 and a runtime ofcomputer software application 152. In an embodiment, receiver 130 isimplemented as computer software executing on a computer system, such asprocessing unit 916 as shown in FIG. 9 such that the computer systemreceives performance requirements data 150 at one of a startup time ofcomputer software application 152 and a runtime of computer softwareapplication 152. In an embodiment, receiver 130 is implemented ascomputer software executing on a computer system, such as a streamcomputing manager system (e.g., a stream runtime system), such that thecomputer system receives performance requirements data 150 at one of astartup time of computer software application 152 and a runtime ofcomputer software application 152. In an embodiment, receiver 130receives performance requirements data 150 at one of a startup time ofcomputer software application 152 and a runtime of computer softwareapplication 152 as computer software executing on a processor/processingunit of receiver 130.

Receiving Metadata

In a particular embodiment, the receiving the performance requirementsdata at the startup time of the computer software application includesreceiving metadata of the processing elements of the computer softwareapplication at the startup time of the computer software application. Ina particular embodiment, receiving operation 110 includes an operationof receiving metadata of the processing elements of the computersoftware application at the startup time of the computer softwareapplication. In an embodiment, receiver 130 is configured to receivemetadata of processing elements 154 of computer software application 152at the startup time of computer software application 152. In anembodiment, receiver 130 includes a computer system, such as computersystem 900 as shown in FIG. 9, receiving metadata of processing elements154 of computer software application 152 at the startup time of computersoftware application 152. In an embodiment, receiver 130 includes acomputer system, such as computer system/server 912 as shown in FIG. 9,receiving metadata of processing elements 154 of computer softwareapplication 152 at the startup time of computer software application152. In an embodiment, receiver 130 includes a computer system, such asprocessing unit 916 as shown in FIG. 9, receiving metadata of processingelements 154 of computer software application 152 at the startup time ofcomputer software application 152. In an embodiment, receiver 130 is astream computing manager system (e.g., a stream runtime system)receiving metadata of processing elements 154 of computer softwareapplication 152 at the startup time of computer software application152.

In an embodiment, receiver 130 is implemented as computer softwareexecuting on a computer system, such as computer system 900 as shown inFIG. 9, such that the computer system receives metadata of processingelements 154 of computer software application 152 at the startup time ofcomputer software application 152. In an embodiment, receiver 130 isimplemented as computer software executing on a computer system, such ascomputer system/server 912 as shown in FIG. 9, such that the computersystem receives metadata of processing elements 154 of computer softwareapplication 152 at the startup time of computer software application152. In an embodiment, receiver 130 is implemented as computer softwareexecuting on a computer system, such as processing unit 916 as shown inFIG. 9 such that the computer system receives metadata of processingelements 154 of computer software application 152 at the startup time ofcomputer software application 152. In an embodiment, receiver 130 isimplemented as computer software executing on a computer system, such asa stream computing manager system (e.g., a stream runtime system), suchthat the computer system receives metadata of processing elements 154 ofcomputer software application 152 at the startup time of computersoftware application 152. In an embodiment, receiver 130 receivesmetadata of processing elements 154 of computer software application 152at the startup time of computer software application 152 as computersoftware executing on a processor/processing unit of receiver 130.

Receiving Resource Characteristics Data

In an exemplary embodiment, the receiving the resource characteristicsdata includes receiving the resource characteristics data at one of astartup time of the computer software application and a runtime of thecomputer software application. In an exemplary embodiment, receivingoperation 112 includes an operation of receiving the resourcecharacteristics data at one of a startup time of the computer softwareapplication and a runtime of the computer software application. In anembodiment, receiver 130 is configured to receive resourcecharacteristics data 160 at one of a startup time of computer softwareapplication 152 and a runtime of computer software application 152. Inan embodiment, receiver 130 includes a computer system, such as computersystem 900 as shown in FIG. 9, receiving resource characteristics data160 at one of a startup time of computer software application 152 and aruntime of computer software application 152. In an embodiment, receiver130 includes a computer system, such as computer system/server 912 asshown in FIG. 9, receiving resource characteristics data 160 at one of astartup time of computer software application 152 and a runtime ofcomputer software application 152. In an embodiment, receiver 130includes a computer system, such as processing unit 916 as shown in FIG.9, receiving resource characteristics data 160 at one of a startup timeof computer software application 152 and a runtime of computer softwareapplication 152. In an embodiment, receiver 130 is a stream computingmanager system (e.g., a stream runtime system) receiving resourcecharacteristics data 160 at one of a startup time of computer softwareapplication 152 and a runtime of computer software application 152.

In an embodiment, receiver 130 is implemented as computer softwareexecuting on a computer system, such as computer system 900 as shown inFIG. 9, such that the computer system receives resource characteristicsdata 160 at one of a startup time of computer software application 152and a runtime of computer software application 152. In an embodiment,receiver 130 is implemented as computer software executing on a computersystem, such as computer system/server 912 as shown in FIG. 9, such thatthe computer system receives resource characteristics data 160 at one ofa startup time of computer software application 152 and a runtime ofcomputer software application 152. In an embodiment, receiver 130 isimplemented as computer software executing on a computer system, such asprocessing unit 916 as shown in FIG. 9 such that the computer systemreceives resource characteristics data 160 at one of a startup time ofcomputer software application 152 and a runtime of computer softwareapplication 152. In an embodiment, receiver 130 is implemented ascomputer software executing on a computer system, such as a streamcomputing manager system (e.g., a stream runtime system), such that thecomputer system receives resource characteristics data 160 at one of astartup time of computer software application 152 and a runtime ofcomputer software application 152. In an embodiment, receiver 130receives resource characteristics data 160 at one of a startup time ofcomputer software application 152 and a runtime of computer softwareapplication 152 as computer software executing on a processor/processingunit of receiver 130.

Receiving Performance Characteristics Data

In an exemplary embodiment, the receiving the performancecharacteristics data includes receiving the performance characteristicsdata at one of a startup time of the computer software application and aruntime of the computer software application. In an exemplaryembodiment, receiving operation 114 includes an operation of receivingthe performance characteristics data at one of a startup time of thecomputer software application and a runtime of the computer softwareapplication. In an embodiment, receiver 130 is configured to receiveperformance characteristics data 170 at one of a startup time ofcomputer software application 152 and a runtime of computer softwareapplication 152. In an embodiment, receiver 130 includes a computersystem, such as computer system 900 as shown in FIG. 9, receivingperformance characteristics data 170 at one of a startup time ofcomputer software application 152 and a runtime of computer softwareapplication 152. In an embodiment, receiver 130 includes a computersystem, such as computer system/server 912 as shown in FIG. 9, receivingperformance characteristics data 170 at one of a startup time ofcomputer software application 152 and a runtime of computer softwareapplication 152. In an embodiment, receiver 130 includes a computersystem, such as processing unit 916 as shown in FIG. 9, receivingperformance characteristics data 170 at one of a startup time ofcomputer software application 152 and a runtime of computer softwareapplication 152. In an embodiment, receiver 130 is a stream computingmanager system (e.g., a stream runtime system) receiving performancecharacteristics data 170 at one of a startup time of computer softwareapplication 152 and a runtime of computer software application 152.

In an embodiment, receiver 130 is implemented as computer softwareexecuting on a computer system, such as computer system 900 as shown inFIG. 9, such that the computer system receives performancecharacteristics data 170 at one of a startup time of computer softwareapplication 152 and a runtime of computer software application 152. Inan embodiment, receiver 130 is implemented as computer softwareexecuting on a computer system, such as computer system/server 912 asshown in FIG. 9, such that the computer system receives performancecharacteristics data 170 at one of a startup time of computer softwareapplication 152 and a runtime of computer software application 152. Inan embodiment, receiver 130 is implemented as computer softwareexecuting on a computer system, such as processing unit 916 as shown inFIG. 9 such that the computer system receives performancecharacteristics data 170 at one of a startup time of computer softwareapplication 152 and a runtime of computer software application 152. Inan embodiment, receiver 130 is implemented as computer softwareexecuting on a computer system, such as a stream computing managersystem (e.g., a stream runtime system), such that the computer systemreceives performance characteristics data 170 at one of a startup timeof computer software application 152 and a runtime of computer softwareapplication 152. In an embodiment, receiver 130 receives performancecharacteristics data 170 at one of a startup time of computer softwareapplication 152 and a runtime of computer software application 152 ascomputer software executing on a processor/processing unit of receiver130.

Assigning Processing Elements

In an exemplary embodiment, the assigning includes (a) for each of thestream computing servers, calculating, by the computer system, at leastone communications characteristic value indicating a characteristic of acommunication channel between the each of the stream computer serversand the at least one computing resource external to the stream computingsystem, resulting in communications characteristics values of the streamcomputing servers, and (2) assigning, by the computer system, the atleast one processing element to the at least one stream computing serverwith a communications characteristic value, among the communicationscharacteristics values of the stream computing servers, that satisfiesrequirements indicated by the performance requirements data of the atleast one processing element with respect to the resourcecharacteristics data of the at least one computing resource external tothe stream computing system and with respect to the performancecharacteristics data of the stream computing servers. Referring to FIG.2, in an exemplary embodiment, assigning operation 116 includes anoperation 210 of for each of the stream computing servers, calculating,by the computer system, at least one communications characteristic valueindicating a characteristic of a communication channel between the eachof the stream computer servers and the at least one computing resourceexternal to the stream computing system, resulting in communicationscharacteristics values of the stream computing servers, and an operation212 of assigning, by the computer system, the at least one processingelement to the at least one stream computing server with acommunications characteristic value, among the communicationscharacteristics values of the stream computing servers, that satisfiesrequirements indicated by the performance requirements data of the atleast one processing element with respect to the resourcecharacteristics data of the at least one computing resource external tothe stream computing system and with respect to the performancecharacteristics data of the stream computing servers. In an embodiment,the at least one communications characteristic value indicates a latencyof the communication channel. In an embodiment, the at least onecommunications characteristic value indicates a distance between theeach of the stream computer servers and the at least one computingresource external to the stream computing system.

In an embodiment, assigner 140 includes a computer system 900 as shownin FIG. 9, that executes an assigning processing elements to streamcomputing servers with respect to external computing resources script orcomputer software application that carries out the operations of atleast method 200. In an embodiment, assigner 140 includes a computersystem/server 912 as shown in FIG. 9, that executes an assigningprocessing elements to stream computing servers with respect to externalcomputing resources script or computer software application that carriesout the operations of at least method 200. In an embodiment, assigner140 includes a processing unit 916 as shown in FIG. 9, that executes anassigning processing elements to stream computing servers with respectto external computing resources script or computer software applicationthat carries out the operations of at least method 200. In anembodiment, assigner 140 is a stream computing manager system (e.g., astream runtime system) that executes an assigning processing elements tostream computing servers with respect to external computing resourcesscript or computer software application that carries out the operationsof at least method 200. In an embodiment, assigner 140 includes acomputer system 900 as shown in FIG. 9, that executes an assigningprocessing elements to stream computing servers with respect to externalcomputing resources script or computer software application that carriesout at least operations 210 and 212. In an embodiment, assigner 140includes a computer system/server 912 as shown in FIG. 9, that executesan assigning processing elements to stream computing servers withrespect to external computing resources script or computer softwareapplication that carries out at least operations 210 and 212. In anembodiment, assigner 140 includes a processing unit 916 as shown in FIG.9, that executes an assigning processing elements to stream computingservers with respect to external computing resources script or computersoftware application that carries out at least operations 210 and 212.In an embodiment, assigner 140 is a stream computing manager system(e.g., a stream runtime system) that executes an assigning processingelements to stream computing servers with respect to external computingresources script or computer software application that carries out atleast operations 210 and 212.

In an embodiment, assigner 140 is configured to calculate, for each ofstream computing servers 158, at least one communications characteristicvalue indicating a characteristic of a communication channel between theeach of stream computer servers 158 and at least one computing resource162 external to stream computing system 156, resulting in communicationscharacteristics values of stream computing servers 158. In anembodiment, assigner 140 includes a computer system, such as computersystem 900 as shown in FIG. 9, performing operation 210. In anembodiment, assigner 140 includes a computer system, such as computersystem/server 912 as shown in FIG. 9, performing operation 210. In anembodiment, assigner 140 includes a computer system, such as processingunit 916 as shown in FIG. 9, performing operation 210. In an embodiment,assigner 140 is a stream computing manager system (e.g., a streamruntime system) performing operation 210. In an embodiment, assigner 140is implemented as computer software executing on a computer system, suchas computer system 900 as shown in FIG. 9, such that the computer systemperforms operation 210. In an embodiment, assigner 140 is implemented ascomputer software executing on a computer system, such as computersystem/server 912 as shown in FIG. 9, such that the computer systemperforms operation 210. In an embodiment, assigner 140 is implemented ascomputer software executing on a computer system, such as processingunit 916 as shown in FIG. 9 such that the computer system performsoperation 210. In an embodiment, assigner 140 is implemented as computersoftware executing on a computer system, such as a stream computingmanager system (e.g., a stream runtime system), such that the computersystem performs operation 210. In an embodiment, assigner 140 performsoperation 210 as computer software executing on a processor/processingunit of assigner 140.

In an embodiment, assigner 140 is configured to assign at least oneprocessing element 155 to at least one stream computing server 159 witha communications characteristic value, among the communicationscharacteristics values of stream computing servers 158, that satisfiesrequirements indicated by performance requirements data 150 of at leastone processing element 155 with respect to resource characteristics data160 of at least one computing resource 162 external to stream computingsystem 156 and with respect to performance characteristics data 170 ofstream computing servers 158. In an embodiment, assigner 140 includes acomputer system, such as computer system 900 as shown in FIG. 9,performing operation 212. In an embodiment, assigner 140 includes acomputer system, such as computer system/server 912 as shown in FIG. 9,performing operation 212. In an embodiment, assigner 140 includes acomputer system, such as processing unit 916 as shown in FIG. 9,performing operation 212. In an embodiment, assigner 140 is a streamcomputing manager system (e.g., a stream runtime system) performingoperation 212. In an embodiment, assigner 140 is implemented as computersoftware executing on a computer system, such as computer system 900 asshown in FIG. 9, such that the computer system performs operation 212.In an embodiment, assigner 140 is implemented as computer softwareexecuting on a computer system, such as computer system/server 912 asshown in FIG. 9, such that the computer system performs operation 212.In an embodiment, assigner 140 is implemented as computer softwareexecuting on a computer system, such as processing unit 916 as shown inFIG. 9 such that the computer system performs operation 212. In anembodiment, assigner 140 is implemented as computer software executingon a computer system, such as a stream computing manager system (e.g., astream runtime system), such that the computer system performs operation212. In an embodiment, assigner 140 performs operation 212 as computersoftware executing on a processor/processing unit of assigner 140.

Stream Computing System

Referring to FIG. 3, in an exemplary embodiment, stream computing system156 includes a computing infrastructure 300 that is configured toexecute a stream computing application (e.g., computer softwareapplication 152). In an embodiment, computing infrastructure 300includes a management system 305 and two or more compute nodes 310A,310B, 310C, 310D (i.e., hosts) (e.g., stream computing servers 158)which are logically and/or communicatively coupled to each other usingone or more communications networks 320. For example, communicationsnetwork 320 could include one or more servers, networks, or databases,and could use a particular communication protocol to transfer databetween compute nodes 310A, 310B, 310C, 310D. In an embodiment, acomputing development system 302 is logically and/or communicativelycoupled with management system 305 and compute nodes 310A, 310B, 310C,310D, either directly or via communications network 320.

For example, communications network 320 could include a variety of typesof physical communication channels or “links”, where the links could bewired, wireless, optical, or any other suitable media. In addition,communications network 320 could include a variety of network hardwareand software for performing routing, switching, and other functions,such as routers, switches, or bridges. Communications network 320 couldbe dedicated for use by a stream computing application (e.g., computersoftware application 152) or shared with other applications and users.Communications network 320 could be any size, such that, for example,communications network 320 could include a single local area network ora wide area network spanning a large geographical area, such as theInternet. In a further example, the links could provide different levelsof bandwidth or capacity to transfer data at a particular rate, wherethe bandwidth that a particular link could provide could vary dependingon a variety of factors (e.g., the type of communication media andwhether particular network hardware or software is functioning correctlyor at full capacity). In addition, for example, the bandwidth that aparticular link could provide to a stream computing application (e.g.,computer software application 152), could vary (a) if the link wereshared with other applications and users, such that the bandwidth coulddepend on the load placed on the link by the other applications andusers and/or (b) depending on a temporal factor (e.g., time of day, dayof week, day of month, or season).

Stream Computing Servers

Referring to FIG. 4, in an exemplary embodiment, each of streamcomputing servers 158 is a compute node 310, which could be the same asone of compute nodes 310A, 310B, 310C, 310D. In an embodiment, computenode 310 includes one or more processors/central processing units (CPUs)405, a network interface 415, an interconnect (bus) 420, a memory 425,and a storage 430 (i.e., storage device). In a further embodiment,compute node 310 includes an input/output (I/O) device interface 410used to connect I/O devices (e.g., keyboard, display, mouse devices) tocompute node 310.

In an embodiment, each CPU 405 retrieves and executes programminginstructions stored in memory 425 or storage 430, and stores andretrieves application data residing in memory 425. In an embodiment,interconnect 420 is used to transmit programming instructions andapplication data between each CPU 405, I/O device interface 410, storage430, network interface 415, and memory 425. For example, interconnect420 could be one or more busses. Also, for example, CPUs 405 could be asingle CPU, multiple CPUs, or a single CPU having multiple processingcores. In a specific example, processor/CPU 405 could be a digitalsignal processor (DSP).

In an embodiment, one or more processing elements 435 (e.g., processingelements 154) are stored in memory 425, where processing element 435includes one or more stream operators 440. In an embodiment, processingelement 435 is assigned to be executed by only one CPU 405. In anembodiment, stream operators 440 of processing element 435 include oneor more threads that are executed on two or more CPUs 405. For example,memory 425 could be a random access memory (e.g., Static Random AccessMemory (SRAM), Dynamic Random Access Memory (DRAM), flash memory). Forexample, storage 430 could be a non-volatile memory (e.g., hard diskdrive, solid state device (SSD), removable memory cards, opticalstorage, flash memory devices, network attached storage (NAS),connections to storage area network (SAN) devices, other devices) thatstores non-volatile data. In an embodiment, network interface 415 isconfigured to transmit data via communications network 320.

In an embodiment, a stream computing application (e.g., computersoftware application 152) includes one or more stream operators 440 thatmay be compiled into a “processing element” container/processingelements 435. In an embodiment, two or more processing elements 435 runon memory 425, such that each processing element 435 has one or morestream operators 440. For example, each stream operator 440 couldinclude a portion of computer software programming code that processestuples flowing into processing element 435 and outputs tuples to otherstream operators 440 in processing element 435, in other processingelements, or in both the same and other processing elements in a streamcomputing application (e.g., computer software application 152). In anembodiment, processing elements 435 pass tuples to other processingelements that are on the same compute node 310 or on other compute nodesthat are accessible via communications network 320. For example, aprocessing element(s) (e.g., processing element 435) on compute node310A could output tuples to a processing element(s) on compute node310B. In an embodiment, storage 430 include a buffer 460. In analternative embodiment, buffer 460 is located in memory 425 of computenode 310 or in a combination of both memories. In an embodiment, storage430 includes storage space that is external to compute node 310, such asin a cloud computing system.

In an embodiment, compute node 310 includes one or more operatingsystems 462. For example, operating system 462 could be stored partiallyin memory 425 and partially in storage 430. In another example,operating system 462 could be stored entirely in memory 425 or entirelyin storage 430. Also, for example, operating system 462 could provide aninterface between various hardware resources, including CPU 405, andprocessing elements 435 and other components of the stream computingapplication (e.g., computer software application 152). In addition,operating system 462 could provide common services for applicationprograms, such as providing a time function.

Management System

Referring to FIG. 5, in an exemplary embodiment, management system 305includes one or more processors/central processing units (CPUs) 505, anetwork interface 515, an interconnect (bus) 520, a memory 525, and astorage 530 (i.e., storage device). In a further embodiment, managementsystem 305 includes an input/output (I/O) device interface 510connecting I/O devices (e.g., keyboard, display, mouse devices) tomanagement system 305.

In an embodiment, each CPU 505 retrieves and executes programminginstructions stored in memory 525 or storage 530, and stores andretrieves application data residing in the memory 525 or storage 530. Inan embodiment, interconnect 520 is used to move data, such asprogramming instructions and application data, between CPU 505, I/Odevice interface 510, storage 530, network interface 515, and memory525. For example, interconnect 520 could be one or more busses. Also,for example, CPUs 505 may be a single CPU, multiple CPUs, or a singleCPU having multiple processing cores. In a specific example,processor/CPU 505 could be a DSP.

For example, memory 525 could be a random access memory (e.g., SRAM,DRAM, flash memory). In another example, storage 530 could be anon-volatile memory (e.g., hard disk drive, solid state device (SSD),removable memory cards, optical storage, flash memory devices, networkattached storage (NAS), connections to storage area-network (SAN)devices, cloud storage). In an embodiment, network interface 515 isconfigured to transmit data via communications network 320. In anembodiment, memory 525 stores stream manager 334. In an embodiment,storage 530 stores operator graph 332. In a particular embodiment,operator graph 332 define how tuples are routed to processing elements435 for processing.

In an embodiment, management system 305 includes one or more operatingsystems 532. For example, operating system 532 could be stored partiallyin memory 525 and partially in storage 530. In another example,operating system 532 could be stored entirely in memory 525 or entirelyin storage 530. Also, for example, operating system 532 could provide aninterface between various hardware resources, including CPU 505, andprocessing elements 435 and other components of the stream computingapplication (e.g., computer software application 152). In addition,operating system 532 could provide common services for applicationprograms, such as providing a time function.

Development System

Referring to FIG. 6, in an exemplary embodiment, development system 302includes one or more processors/central processing units (CPUs) 605, anetwork interface 615, an interconnect (bus) 620, a memory 625, and astorage 630 (i.e., storage device). In a further embodiment, developmentsystem 302 includes an input/output (I/O) device interface 610connecting I/O devices (e.g., keyboard, display, mouse devices) todevelopment system 302.

In an embodiment, CPU 605 retrieves and executes programminginstructions stored in memory 625 or storage 630, and stores andretrieves application data residing in memory 625 or storage 630. In anembodiment, interconnect 620 is used to move data, such as programminginstructions and application data, between the CPU 605, I/O deviceinterface 610, storage 630, network interface 615, and memory 625. Forexample, interconnect 620 could be one or more busses. Also, forexample, CPUs 605 may be a single CPU, multiple CPUs, or a single CPUhaving multiple processing cores. In a specific example, processor/CPU605 could be a DSP.

For example, memory 625 could be a random access memory (e.g., SRAM,DRAM, flash memory). In another example, storage 630 could be anon-volatile memory (e.g., hard disk drive, solid state device (SSD),removable memory cards, optical storage, flash memory devices, networkattached storage (NAS), connections to storage area-network (SAN)devices, cloud storage). In an embodiment, network interface 615 isconfigured to transmit data via communications network 320.

In an embodiment, development system 302 includes one or more operatingsystems 632. For example, operating system 632 may be stored partiallyin memory 625 and partially in storage 630. In another example,operating system 632 could be stored entirely in memory 625 or entirelyin storage 630. Also, for example, operating system 632 could provide aninterface between various hardware resources, including CPU 605, andprocessing elements 435 and other components of the stream computingapplication (e.g., computer software application 152). In addition,operating system 632 could provide common services for applicationprograms, such as providing a time function.

In an embodiment, memory 625 stores compiler 336. In a particularembodiment, compiler 336 compiles modules, which include source code orstatements, into the object code, which includes machine instructionsthat execute on a processor/CPU. For example, compiler 336 couldtranslate the modules into an intermediate form before translating theintermediate form into object code. In another example, compiler 336could output a set of deployable artifacts that could include a set ofprocessing elements and an application description language file (ADLfile), which is a configuration file that describes the stream computingapplication (e.g., computer software application 152). For example,compiler 336 could be a just-in-time compiler that executes as part ofan interpreter. In another example, compiler 336 could be an optimizingcompiler. For example, compiler 336 could perform peepholeoptimizations, local optimizations, loop optimizations, inter-proceduralor whole-program optimizations, machine code optimizations, or any otheroptimizations that reduce the amount of time required to execute theobject code, to reduce the amount of memory required to execute theobject code, or both. In an embodiment, the output of compiler 336 maybe represented by an operator graph, (e.g., operator graph 332).

In an embodiment, compiler 336 provides an application administratorwith the ability to optimize performance through profile-driven fusionoptimization. For example, fusing operators could improve performance byreducing the number of calls to a transport. In a further example, whilefusing stream operators could provide faster communication betweenoperators than could be available using inter-process communicationtechniques, a decision to fuse operators could require balancing thebenefits of distributing processing across multiple compute nodes withthe benefit of faster inter-operator communications. In an embodiment,compiler 336 automates the fusion process to determine how to best fusethe operators to be hosted by one or more processing elements (e.g.,processing elements 435), while respecting user-specified constraints.For example, automating the fusion process could be a two-step process,including compiling the application in a profiling mode and running theapplication, then re-compiling and using the optimizer during thissubsequent compilation, with the end result perhaps being acompiler-supplied deployable application with an optimized applicationconfiguration.

Operator Graph

Referring to FIG. 7, in an exemplary embodiment, operator graph 332 isan operator graph 700 for a stream computing application (e.g., computersoftware application 152) beginning from one or more sources 702 (i.e.,operator sources) through to one or more sinks 704, 706 (i.e., operatorsinks). For example, the flow from one or more sources 702 through toone or more sinks 704, 706 could be an execution path, while a flow fromone processing element (e.g., processing elements 154, 155, 435, PE1,PE2, PE3, PE4, PE5, PE6, PE7, PE8, PE9, PE10) to another (e.g.,processing elements 154, 435, PE1, PE2, PE3, PE4, PE5, PE6, PE7, PE8,PE9, PE10) could be an execution path. In an embodiment, operator graph700 includes connected processing elements PE1, PE2, PE3, PE4, PE5, PE6,PE7, PE8, PE9, and PE10. In an embodiment, operator graph 700 includesdata flows between stream operators 440 within the same or differentprocessing elements (e.g., processing elements 154, 435, PE1, PE2, PE3,PE4, PE5, PE6, PE7, PE8, PE9, PE10). For example, processing elements154, 435 (e.g., processing elements PE1, PE2, PE3, PE4, PE5, PE6, PE7,PE8, PE9, PE10) could receive tuples from a stream as well as outputtuples into the stream (except for a sink (e.g., sink 704, 706) (wherethe stream terminates), or a source (e.g., source 702) (where the streambegins)). In another example, operator graph 700 could include manyindividual operator graphs that may be statically or dynamically linkedtogether.

In an embodiment, operator graph 700 includes processing elements PE1,PE2, PE3, PE4, PE5, PE6, PE7, PE8, PE9, PE10 running on compute nodes310A, 310B, 310C, 310D. In a particular embodiment, a processing element(e.g., processing element 155) among processing elements 154, 435 (e.g.,processing elements PE1, PE2, PE3, PE4, PE5, PE6, PE7, PE8, PE9, PE10)includes one or more stream operators 440 fused together to form anindependently running process with its own process identifier (ID) (PID)and memory space. For example, if two (or more) processing elements 154,435 were running independently, inter-process communication could occurusing a “transport” (e.g., network socket, TCP/IP socket, sharedmemory). In a further example, inter-process communication paths usedfor inter-process communications could be a resource in a streamcomputing application (e.g., computer software application 152). In anexample, if stream operators were fused together, the fused streamoperators could use more rapid communication techniques for passingtuples among stream operators in each processing element 154, 435.

In an embodiment, operator graph 700 begins at source 702 and ends atsink 704, 706. For example, compute node 310A could processing elementsPE1, PE2, and PE3, with source 702 flowing into processing element PE1,with processing element PE1 outputting tuples that are received byprocessing elements PE2 and PE3. In a further example, processingelement PE1 could split data attributes received in a tuple and passsome data attributes in a new tuple to processing element PE2, whilepassing other data attributes in another new tuple to processing elementPE3. In another example, processing element PE1 could pass some receivedtuples to processing element PE2 while passing other tuples toprocessing element PE3. In a further example, stream operators (e.g.,stream operators 440) contained in processing element PE2 could processtuples that flow to processing element PE2, with processing element PE2outputting the resulting tuples to processing element PE4 on computenode 310B. In addition, for example, the tuples outputted by processingelement PE4 could flow to sink 704 via processing element PE6 (i.e., asink processing element). Also, for example, tuples flowing fromprocessing element PE3 to processing element PE5 could flow to sink 704via processing element PE6 (i.e., a sink processing element). Thus, forexample, processing element PE6 could be a sink for operator graph 700and could be configured to perform a join operation, combining tuplesreceived from processing elements PE4 and PE5. In a further example,tuples could flow from processing element PE3 to processing element PE7on compute node 310C, with tuples flowing from processing element PE7 toprocessing element PE8 and looping back to processing element PE7. In afurther example, tuples outputted from processing element PE8 could flowto processing element PE9 on compute node 310D, with compute node 310Doutputting tuples to be processed by operators in a sink processingelement (e.g., processing element PE10, sink 706).

For example, the tuple received by a particular processing element 154,435 may not be the same tuple that is outputted downstream since theoutput tuple could be changed in some way. In a specific example, anattribute or metadata in the output tuple could be added, deleted, orchanged (e.g., by a processing element). In another example, aparticular tuple output by a processing element (e.g., processingelements 154, 435, PE1, PE2, PE3, PE4, PE5, PE6, PE7, PE8, PE9, PE10)may not be the same tuple as a corresponding input tuple even if theinput tuple were not changed by the processing element. In an example,an output tuple that has the same data attributes as a correspondinginput tuple could be the same tuple.

In an embodiment, processing elements 154, 435 are configured to receiveor output tuples in various formats (e.g., processing elements or streamoperators could exchange data marked up as XML documents). For example,each stream operator 440 within a processing element 154, 435 couldcarry out any form of data processing functions on received tuples(e.g., writing to database tables, performing other database operations(e.g., data joins, splits, reads) and could perform other data analyticfunctions or operations.

In an embodiment, stream manager 334 is configured to monitor a streamcomputing application (e.g., computer software application 152) runningon compute nodes (e.g., compute nodes 310A, 310B, 310C, 310D) and isconfigured to change the deployment of an operator graph (e.g., operatorgraph 332). For example, stream manager 334 could move processingelements 154, 435 from one compute node 310 to another, for example, tomanage the processing loads of compute nodes 310A, 310B, 310C, 310D. Ina further example, stream manager 334 could control the stream computingapplication (e.g., computer software application 152) by inserting,removing, fusing, un-fusing, or otherwise modifying processing elements154, 435 and stream operators 440 (or what tuples flow to processingelements 154, 435) running on compute nodes 310A, 310B, 310C, 310D. Inan example, processing element 154, 435, could be a collection of fusedstream operators. In specific example, operator graph 332, 700 couldinclude one or more execution paths between specific stream operators440, which could include execution paths to different stream operators440 within the same processing element 154, 435.

EXAMPLE

FIG. 8 depicts an example of the present invention with stream manager334 assigning processing elements 810 (e.g., processing element 155) toa stream computing server 812 (SCS 812) (e.g., stream computing server159) in stream computing system 156 so that processing elements 810(e.g., processing element 155) could access/make use of computingresource 162 (e.g., a data sink/source). For example, the presentinvention (e.g., via stream manager 334) could placeoperators/processing elements (e.g., processing element 155, processingelements 810) onto stream computing servers (e.g., stream computingservers 158, 159, 812) via the following configuration statement: configplacement: hostColocation(“someHostColocationId”)type(with_external_source_time,<database system>,10 nanoseconds). Viasuch a configuration statement, for example, the present invention coulddirect stream computing system 156 to place a processing element (e.g.,processing element 155, processing elements 810) in a distance thatwould achieve 10 nanosecond latency to some database designated by thename <database system> (e.g., computing resource 162). In its simplestform, the present invention could require a ping command to the externalsource (e.g., computing resource 162) to come back within 10 nanosecondbetween the two systems in order to place operators/processing elements(e.g., processing element 155, processing elements 810) on a particularstream computing server (e.g., stream computing server 159, 812). Inanother example, the present invention could place processing elements(e.g., processing element 155, processing elements 810) at the“quickest” node in the cluster/network of stream computing servers(e.g., stream computing servers 158), or at the “farthest” node withinthe cluster/network of stream computing servers (e.g., stream computingservers 158).

Computer System

In an exemplary embodiment, the computer system is a computer system 900as shown in FIG. 9. Computer system 900 is only one example of acomputer system and is not intended to suggest any limitation as to thescope of use or functionality of embodiments of the present invention.Regardless, computer system 900 is capable of being implemented toperform and/or performing any of the functionality/operations of thepresent invention.

Computer system 900 includes a computer system/server 912, which isoperational with numerous other general purpose or special purposecomputing system environments or configurations. Examples of well-knowncomputing systems, environments, and/or configurations that may besuitable for use with computer system/server 912 include, but are notlimited to, personal computer systems, server computer systems, thinclients, thick clients, hand-held or laptop devices, multiprocessorsystems, microprocessor-based systems, set top boxes, programmableconsumer electronics, network PCs, minicomputer systems, mainframecomputer systems, and distributed cloud computing environments thatinclude any of the above systems or devices.

Computer system/server 912 may be described in the general context ofcomputer system-executable instructions, such as program modules, beingexecuted by a computer system. Generally, program modules may includeroutines, programs, objects, components, logic, and/or data structuresthat perform particular tasks or implement particular abstract datatypes. Computer system/server 912 may be practiced in distributed cloudcomputing environments where tasks are performed by remote processingdevices that are linked through a communications network. In adistributed cloud computing environment, program modules may be locatedin both local and remote computer system storage media including memorystorage devices.

As shown in FIG. 9, computer system/server 912 in computer system 900 isshown in the form of a general-purpose computing device. The componentsof computer system/server 912 may include, but are not limited to, oneor more processors or processing units 916, a system memory 928, and abus 918 that couples various system components including system memory928 to processor 916.

Bus 918 represents one or more of any of several types of busstructures, including a memory bus or memory controller, a peripheralbus, an accelerated graphics port, and a processor or local bus usingany of a variety of bus architectures. By way of example, and notlimitation, such architectures include Industry Standard Architecture(ISA) bus, Micro Channel Architecture (MCA) bus, Enhanced ISA (EISA)bus, Video Electronics Standards Association (VESA) local bus, andPeripheral Component Interconnects (PCI) bus.

Computer system/server 912 typically includes a variety of computersystem readable media. Such media may be any available media that isaccessible by computer system/server 912, and includes both volatile andnon-volatile media, removable and non-removable media.

System memory 928 can include computer system readable media in the formof volatile memory, such as random access memory (RAM) 830 and/or cachememory 932. Computer system/server 912 may further include otherremovable/non-removable, volatile/non-volatile computer system storagemedia. By way of example only, storage system 934 can be provided forreading from and writing to a non-removable, non-volatile magnetic media(not shown and typically called a “hard drive”). Although not shown, amagnetic disk drive for reading from and writing to a removable,non-volatile magnetic disk (e.g., a “floppy disk”), and an optical diskdrive for reading from or writing to a removable, non-volatile opticaldisk such as a CD-ROM, DVD-ROM or other optical media can be provided.In such instances, each can be connected to bus 918 by one or more datamedia interfaces. As will be further depicted and described below,memory 928 may include at least one program product having a set (e.g.,at least one) of program modules that are configured to carry out thefunctions/operations of embodiments of the invention.

Program/utility 940, having a set (at least one) of program modules 942,may be stored in memory 928 by way of example, and not limitation.Exemplary program modules 942 may include an operating system, one ormore application programs, other program modules, and program data. Eachof the operating system, one or more application programs, other programmodules, and program data or some combination thereof, may include animplementation of a networking environment. Program modules 942generally carry out the functions and/or methodologies of embodiments ofthe present invention.

Computer system/server 912 may also communicate with one or moreexternal devices 914 such as a keyboard, a pointing device, a display924, one or more devices that enable a user to interact with computersystem/server 912, and/or any devices (e.g., network card, modem, etc.)that enable computer system/server 912 to communicate with one or moreother computing devices. Such communication can occur via Input/Output(I/O) interfaces 922. Still yet, computer system/server 912 cancommunicate with one or more networks such as a local area network(LAN), a general wide area network (WAN), and/or a public network (e.g.,the Internet) via network adapter 920. As depicted, network adapter 920communicates with the other components of computer system/server 912 viabus 918. It should be understood that although not shown, other hardwareand/or software components could be used in conjunction with computersystem/server 912. Examples, include, but are not limited to: microcode,device drivers, redundant processing units, external disk drive arrays,RAID systems, tape drives, and data archival storage systems.

Cloud Computing

It is understood in advance that although this disclosure includes adetailed description on cloud computing, implementation of the teachingsrecited herein are not limited to a cloud computing environment. Rather,embodiments of the present invention are capable of being implemented inconjunction with any other type of computing environment now known orlater developed.

Cloud computing is a model of service delivery for enabling convenient,on-demand network access to a shared pool of configurable computingresources (e.g. networks, network bandwidth, servers, processing,memory, storage, applications, virtual machines, and services) that canbe rapidly provisioned and released with minimal management effort orinteraction with a provider of the service. This cloud model may includeat least five characteristics, at least three service models, and atleast four deployment models.

Characteristics are as follows:

On-demand self-service: a cloud consumer can unilaterally provisioncomputing capabilities, such as server time and network storage, asneeded automatically without requiring human interaction with theservice's provider.

Broad network access: capabilities are available over a network andaccessed through standard mechanisms that promote use by heterogeneousthin or thick client platforms (e.g., mobile phones, laptops, and PDAs).

Resource pooling: the provider's computing resources are pooled to servemultiple consumers using a multi-tenant model, with different physicaland virtual resources dynamically assigned and reassigned according todemand. There is a sense of location independence in that the consumergenerally has no control or knowledge over the exact location of theprovided resources but may be able to specify location at a higher levelof abstraction (e.g., country, state, or datacenter).

Rapid elasticity: capabilities can be rapidly and elasticallyprovisioned, in some cases automatically, to quickly scale out andrapidly released to quickly scale in. To the consumer, the capabilitiesavailable for provisioning often appear to be unlimited and can bepurchased in any quantity at any time.

Measured service: cloud systems automatically control and optimizeresource use by leveraging a metering capability at some level ofabstraction appropriate to the type of service (e.g., storage,processing, bandwidth, and active user accounts). Resource usage can bemonitored, controlled, and reported providing transparency for both theprovider and consumer of the utilized service.

Service Models are as follows:

Software as a Service (SaaS): the capability provided to the consumer isto use the provider's applications running on a cloud infrastructure.The applications are accessible from various client devices through athin client interface such as a web browser (e.g., web-based e-mail).The consumer does not manage or control the underlying cloudinfrastructure including network, servers, operating systems, storage,or even individual application capabilities, with the possible exceptionof limited user-specific application configuration settings.

Platform as a Service (PaaS): the capability provided to the consumer isto deploy onto the cloud infrastructure consumer-created or acquiredapplications created using programming languages and tools supported bythe provider. The consumer does not manage or control the underlyingcloud infrastructure including networks, servers, operating systems, orstorage, but has control over the deployed applications and possiblyapplication hosting environment configurations.

Infrastructure as a Service (IaaS): the capability provided to theconsumer is to provision processing, storage, networks, and otherfundamental computing resources where the consumer is able to deploy andrun arbitrary software, which can include operating systems andapplications. The consumer does not manage or control the underlyingcloud infrastructure but has control over operating systems, storage,deployed applications, and possibly limited control of select networkingcomponents (e.g., host firewalls).

Deployment Models are as follows:

Private cloud: the cloud infrastructure is operated solely for anorganization. It may be managed by the organization or a third party andmay exist on-premises or off-premises.

Community cloud: the cloud infrastructure is shared by severalorganizations and supports a specific community that has shared concerns(e.g., mission, security requirements, policy, and complianceconsiderations). It may be managed by the organizations or a third partyand may exist on-premises or off-premises.

Public cloud: the cloud infrastructure is made available to the generalpublic or a large industry group and is owned by an organization sellingcloud services.

Hybrid cloud: the cloud infrastructure is a composition of two or moreclouds (private, community, or public) that remain unique entities butare bound together by standardized or proprietary technology thatenables data and application portability (e.g., cloud bursting forload-balancing between clouds).

A cloud computing environment is service oriented with a focus onstatelessness, low coupling, modularity, and semantic interoperability.At the heart of cloud computing is an infrastructure comprising anetwork of interconnected nodes.

Referring now to FIG. 10, illustrative cloud computing environment 50 isdepicted. As shown, cloud computing environment 50 includes one or morecloud computing nodes 10 with which local computing devices used bycloud consumers, such as, for example, personal digital assistant (PDA)or cellular telephone 54A, desktop computer 54B, laptop computer 54C,and/or automobile computer system 54N may communicate. Nodes 10 maycommunicate with one another. They may be grouped (not shown) physicallyor virtually, in one or more networks, such as Private, Community,Public, or Hybrid clouds as described hereinabove, or a combinationthereof. This allows cloud computing environment 50 to offerinfrastructure, platforms and/or software as services for which a cloudconsumer does not need to maintain resources on a local computingdevice. It is understood that the types of computing devices 54A-N shownin FIG. 10 are intended to be illustrative only and that computing nodes10 and cloud computing environment 50 can communicate with any type ofcomputerized device over any type of network and/or network addressableconnection (e.g., using a web browser).

Referring now to FIG. 11, a set of functional abstraction layersprovided by cloud computing environment 50 is shown. It should beunderstood in advance that the components, layers, and functions shownin FIG. 10 are intended to be illustrative only and embodiments of theinvention are not limited thereto. As depicted, the following layers andcorresponding functions are provided:

Hardware and software layer 60 includes hardware and softwarecomponents. Examples of hardware components include: mainframes; RISC(Reduced Instruction Set Computer) architecture based servers; storagedevices; networks and networking components. In some embodiments,software components include network application server software.

Virtualization layer 62 provides an abstraction layer from which thefollowing examples of virtual entities may be provided: virtual servers;virtual storage; virtual networks, including virtual private networks;virtual applications and operating systems; and virtual clients.

In one example, management layer 64 may provide the functions describedbelow. Resource provisioning provides dynamic procurement of computingresources and other resources that are utilized to perform tasks withinthe cloud computing environment. Metering and Pricing provide costtracking as resources are utilized within the cloud computingenvironment, and billing or invoicing for consumption of theseresources. In one example, these resources may include applicationsoftware licenses. Security provides identity verification for cloudconsumers and tasks, as well as protection for data and other resources.User portal provides access to the cloud computing environment forconsumers and system administrators. Service level management providescloud computing resource allocation and management such that requiredservice levels are met. Service Level Agreement (SLA) planning andfulfillment provide pre-arrangement for, and procurement of, cloudcomputing resources for which a future requirement is anticipated inaccordance with an SLA.

Workloads layer 66 provides examples of functionality for which thecloud computing environment may be utilized. Examples of workloads andfunctions which may be provided from this layer include: mapping andnavigation; software development and lifecycle management; virtualclassroom education delivery; data analytics processing; transactionprocessing; and mobile desktop.

Computer Program Product

The present invention may be a system, a method, and/or a computerprogram product. The computer program product may include a computerreadable storage medium (or media) having computer readable programinstructions thereon for causing a processor to carry out aspects of thepresent invention.

The computer readable storage medium can be a tangible device that canretain and store instructions for use by an instruction executiondevice. The computer readable storage medium may be, for example, but isnot limited to, an electronic storage device, a magnetic storage device,an optical storage device, an electromagnetic storage device, asemiconductor storage device, or any suitable combination of theforegoing. A non-exhaustive list of more specific examples of thecomputer readable storage medium includes the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a static random access memory (SRAM), a portablecompact disc read-only memory (CD-ROM), a digital versatile disk (DVD),a memory stick, a floppy disk, a mechanically encoded device such aspunch-cards or raised structures in a groove having instructionsrecorded thereon, and any suitable combination of the foregoing. Acomputer readable storage medium, as used herein, is not to be construedas being transitory signals per se, such as radio waves or other freelypropagating electromagnetic waves, electromagnetic waves propagatingthrough a waveguide or other transmission media (e.g., light pulsespassing through a fiber-optic cable), or electrical signals transmittedthrough a wire.

Computer readable program instructions described herein can bedownloaded to respective computing/processing devices from a computerreadable storage medium or to an external computer or external storagedevice via a network, for example, the Internet, a local area network, awide area network and/or a wireless network. The network may comprisecopper transmission cables, optical transmission fibers, wirelesstransmission, routers, firewalls, switches, gateway computers and/oredge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device.

Computer readable program instructions for carrying out operations ofthe present invention may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, or either source code or object code written in anycombination of one or more programming languages, including an objectoriented programming language such as Smalltalk, C++ or the like, andconventional procedural programming languages, such as the “C”programming language or similar programming languages. The computerreadable program instructions may execute entirely on the user'scomputer, partly on the user's computer, as a stand-alone softwarepackage, partly on the user's computer and partly on a remote computeror entirely on the remote computer or server. In the latter scenario,the remote computer may be connected to the user's computer through anytype of network, including a local area network (LAN) or a wide areanetwork (WAN), or the connection may be made to an external computer(for example, through the Internet using an Internet Service Provider).In some embodiments, electronic circuitry including, for example,programmable logic circuitry, field-programmable gate arrays (FPGA), orprogrammable logic arrays (PLA) may execute the computer readableprogram instructions by utilizing state information of the computerreadable program instructions to personalize the electronic circuitry,in order to perform aspects of the present invention.

Aspects of the present invention are described herein with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems), and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer readable program instructions.

These computer readable program instructions may be provided to aprocessor of a general purpose computer, special purpose computer, orother programmable data processing apparatus to produce a machine, suchthat the instructions, which execute via the processor of the computeror other programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks. These computer readable program instructionsmay also be stored in a computer readable storage medium that can directa computer, a programmable data processing apparatus, and/or otherdevices to function in a particular manner, such that the computerreadable storage medium having instructions stored therein comprises anarticle of manufacture including instructions which implement aspects ofthe function/act specified in the flowchart and/or block diagram blockor blocks.

The computer readable program instructions may also be loaded onto acomputer, other programmable data processing apparatus, or other deviceto cause a series of operational steps to be performed on the computer,other programmable apparatus or other device to produce a computerimplemented process, such that the instructions which execute on thecomputer, other programmable apparatus, or other device implement thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

The flowchart and block diagrams in the figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof instructions, which comprises one or more executable instructions forimplementing the specified logical function(s). In some alternativeimplementations, the functions noted in the block may occur out of theorder noted in the figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts or carry out combinations of special purpose hardwareand computer instructions.

The descriptions of the various embodiments of the present disclosurehave been presented for purposes of illustration, but are not intendedto be exhaustive or limited to the embodiments disclosed. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope and spirit of the describedembodiments. The terminology used herein was chosen to explain theprinciples of the embodiments, the practical application or technicalimprovement over technologies found in the marketplace, or to enableothers of ordinary skill in the art to understand the embodimentsdisclosed herein.

What is claimed is:
 1. A computer implemented method comprising:receiving, by a computer system, performance requirements data of aplurality of processing elements of a computer software application,wherein the processing elements are configured to execute on a streamcomputing system, wherein the stream computing system comprises anetwork of stream computing servers; receiving, by the computer system,resource characteristics data of at least one computing resourceexternal to the stream computing system; receiving, by the computersystem, performance characteristics data of the stream computingservers; calculating, by the computer system and for each of the streamcomputing servers, at least one communications characteristic valueindicating a characteristic of a communication channel between the eachof the stream computing servers and the at least one computing resourceexternal to the stream computing system, resulting in communicationscharacteristics values of the stream computing servers; and in responseto receiving, by the computer system, a request from at least oneprocessing element among the processing elements to communicate with theat least one computing resource external to the stream computing system,assigning, by the computer system, the at least one processing elementto the at least one stream computing server with a communicationscharacteristic value that satisfies requirements indicated by theperformance requirements data of the at least one processing elementwith respect to the resource characteristics data of the at least onecomputing resource external to the stream computing system and withrespect to the performance characteristics data of the stream computingservers, wherein the communications characteristic value indicates adistance between the at least one stream computing server and the atleast one computing resource external to the stream computing system. 2.The method of claim 1 wherein the receiving the performance requirementsdata comprises receiving the performance requirements data at one of astartup time of the computer software application and a runtime of thecomputer software application.
 3. The method of claim 2 wherein thereceiving the performance requirements data at the startup time of thecomputer software application comprises receiving metadata of theprocessing elements of the computer software application at the startuptime of the computer software application.
 4. The method of claim 1wherein the receiving the resource characteristics data comprisesreceiving the resource characteristics data at one of a startup time ofthe computer software application and a runtime of the computer softwareapplication.
 5. The method of claim 1 wherein the receiving theperformance characteristics data comprises receiving the performancecharacteristics data at one of a startup time of the computer softwareapplication and a runtime of the computer software application.
 6. Themethod of claim 1 wherein the at least one computing resource externalto the stream computing system comprises a computer data source/sink. 7.The method of claim 6 wherein the computer data source/sink is at leastone of a computer database, a computer message queue, a computer storagedevice, a sensor, a camera, and a microphone.
 8. The method of claim 1wherein the at least one communications characteristic value furtherindicates a latency of the communication channel.
 9. A systemcomprising: a memory; and a processor in communication with the memory,the processor configured to perform a method comprising, receivingperformance requirements data of a plurality of processing elements of acomputer software application, wherein the processing elements areconfigured to execute on a stream computing system, wherein the streamcomputing system comprises a network of stream computing servers,receiving resource characteristics data of at least one computingresource external to the stream computing system, receiving performancecharacteristics data of the stream computing servers, calculating, bythe computer system and for each of the stream computing servers, atleast one communications characteristic value indicating acharacteristic of a communication channel between the each of the streamcomputing servers and the at least one computing resource external tothe stream computing system, resulting in communications characteristicsvalues of the stream computing servers; and in response to receiving arequest from at least one processing element among the processingelements to communicate with the at least one computing resourceexternal to the stream computing system, assigning the at least oneprocessing element to the at least one stream computing server with acommunications characteristic value that satisfies requirementsindicated by the performance requirements data of the at least oneprocessing element with respect to the resource characteristics data ofthe at least one computing resource external to the stream computingsystem and with respect to the performance characteristics data of thestream computing servers, wherein the at least one communicationscharacteristic value indicates a distance between the each of the streamcomputing servers and the at least one computing resource external tothe stream computing system.
 10. The system of claim 9 wherein thereceiving the performance requirements data comprises receiving theperformance requirements data at one of a startup time of the computersoftware application and a runtime of the computer software application.11. The system of claim 10 wherein the receiving the performancerequirements data at the startup time of the computer softwareapplication comprises receiving metadata of the processing elements ofthe computer software application at the startup time of the computersoftware application.
 12. The system of claim 9 wherein the receivingthe resource characteristics data comprises receiving the resourcecharacteristics data at one of a startup time of the computer softwareapplication and a runtime of the computer software application.
 13. Thesystem of claim 9 wherein the receiving the performance characteristicsdata comprises receiving the performance characteristics data at one ofa startup time of the computer software application and a runtime of thecomputer software application.
 14. The system of claim 9 wherein the atleast one computing resource external to the stream computing systemcomprises a computer data source/sink.
 15. The system of claim 14wherein the computer data source/sink is at least one of a computerdatabase, a computer message queue, a computer storage device, a sensor,a camera, and a microphone.
 16. A computer program product comprising acomputer readable storage medium having program instructions embodiedtherewith, the program instructions executable by a processor to causethe processor to perform a method comprising: receiving performancerequirements data of a plurality of processing elements of a computersoftware application, wherein the processing elements are configured toexecute on a stream computing system, wherein the stream computingsystem comprises a network of stream computing servers; receivingresource characteristics data of at least one a computing resourceexternal to the stream computing system; receiving performancecharacteristics data of the stream computing servers; calculating, bythe computer system and for each of the stream computing servers, atleast one communications characteristic value that indicates, for eachparticular communications characteristic value, a characteristic of acommunication channel between a particular stream computing server ofthe stream computing servers and the computing resource external to thestream computing system, resulting in communications characteristicsvalues of the stream computing servers; assigning, in response toreceiving a request from a first processing element among the processingelements to communicate with the computing resource external to thestream computing system, the first processing element to a first streamcomputing server with a first communications characteristic value thatsatisfies requirements indicated by the performance requirements data ofthe first processing element with respect to the resourcecharacteristics data of the computing resource external to the streamcomputing system and with respect to the performance characteristicsdata of the stream computing servers; determining that a secondprocessing element does not require communication with the computingresource external to the stream computing system; and assigning, inresponse to the determining, the second processing element to a secondstream computing server without considering a second communicationscharacteristic value, wherein the second communications characteristicvalue indicates a characteristic of a communication channel between thesecond stream computing server and the computing resource.
 17. Thecomputer program product of claim 16, wherein the first stream computingserver and the second stream computing server are the same streamcomputing server.
 18. The computer program product of claim 17, whereinthe first communications characteristic value and the secondcommunications characteristic value are the same communicationscharacteristic value.